While at the Institut de Biologie Structurale, Prof Smith will divide his time among three different activities. Approximately one third of his time will be devoted to the principal goal of the sabbatical leave, interacting with structural biologists using X-ray crystallography, nuclear magnetic resonance, cryo- electron microscopy and molecular biology. He will also spend approximately one third of his time co-directing the research of one graduate student (Florestan Desmaris) and one postdoctoral research associate (Dr. Jean Armengaud). Both use HX MS to detect conformational changes in proteins and are under the supervision of Dr. Eric Forest, Director to of the Laboratoire de Spectrometrie de Masse des Proteines at IBS. This activity is expected to be the basis for a fruitful exchange on experimental details of HX MS methodology. The remaining third of Prof. Smith's effort will be required to direct his on-going research program in HX MS at the University of Nebraska. This research group, which consists of approximately 10 graduate students, four postdoctoral research associates and three permanent staff, is funded principally by two NIH grants (ROI GM 40384 and RO1 EY07609).